In the prior art, it is known to use a wood having an oven-dry specific gravity of about 0.5, such as lauan, radiata pine, Japanese larch, Japanese red pine, or Oregon pine, as a wood for producing a laminated composite lumber as a building material (see, for example, Proceedings of the 40th Anniversary Meeting of the Japan Wood Society, p.246 J3-1040-1, April 1995). A wood having an oven-dry specific gravity of 0.6 or larger not only takes time and labor to transport because it is too heavy, but also is difficult to work on because it is too hard. On the other hand, with a wood having an oven-dry specific gravity of 0.4 or less, it is difficult to secure the desired bending strength and nail holding power. Accordingly, in the case of timbers from South East Asia, only specific kinds of trees, such as lauan, have been logged and used extensively, and as a result, tropical timber trees are being rapidly depleted, this being one of major causes for destruction of natural environments.